Accessibility
New Triple tap to enter full screen magnification when you enable 'Magnification gestures'.
New Enable ‘TalkBack’, a screenreader for Android, right from the power menu.

Camera and Gallery
New Android 4.2 features a completely redesigned camera app with new tools for taking photos.
New High Dynamic Range or HDR mode (on supported devices) lets you see more detail in your shots by widening the exposure range.
New A brand new photo editor features new filters, borders, and other tools to easily customize your photos.
New With Photo Sphere you can take immersive 360º images and wide angle shots that you can view and share on your phone, tablet or desktop computer.
New Access camera straight from your phone’s lock screen.

Clock
New The clock has been totally redesigned with an all new look which includes both a digital and analog clock style.
New You can use the new stopwatch to track time, count laps and splits, and share your times.
New You can use the new timer to keep track of predetermined periods of time, run multiple timers at once, and even label your timers.
New The world clock lets you check the time in different cities right from the Clock app or your lock screen.
New New clock widgets let you choose from an analog or digital clock widget. You can also resize the digital clock widget to display the time in other cities around the world.

Graphics
New Platform level support for new wireless display settings implemented on Nexus 4, including the ability to discover and connect to Miracast™ compatible devices via Wi-Fi Direct.
New Full HDMI mirroring with notifications and multi-display support.

Internationalization
New Android 4.2 brings improved font positioning, glyph cache performance, and more accurate placement of accents in Indic, Hebrew, Arabic, Thai and Latin font kerning.
New New fonts have been added including Roboto Thin and Nanum Gothic for improved Korean font quality.

Keyboard
New Android 4.2 introduces an all new Gesture Keyboard that lets you glide over letters to type a word while it dynamically predicts what you want to type.
New French, English and Russian dictionaries are even more accurate and relevant, while new dictionaries have been added in Danish, Greek, Finnish, Lithuanian, Latvian, Polish, Slovenian, Serbian, Swedish and Turkish.

Lock Screen
New Android 4.2 lets you place widgets on your device's lock screen to give you faster access to your calendar, Gmail, SMS messages, and even third party app widgets.
New Quickly launch Google Now by swiping up from the bottom edge of your secure lock screen.
New Easily access camera straight from your phone’s lock screen.

Messaging and Talk
New Support for group messaging via MMS.

Networking
New Wi-Fi Direct support has been improved, so your device can now remember other devices.
New Faster captive portal detection on Wi-Fi, cellular connections, and pay-as-you-go SIMs.

Phone
New Use the phone app in landscape orientation or while in a car dock.
New With new filtering options you can quickly manage and review your call log.
New Improved TalkBack support with a single tap dialpad.

Settings
New Access Settings by tapping the Quick Settings icon in the notification shade, or swipe down from the top right on tablets or with two fingers on phones to access settings.
New Now quickly toggle Wi-Fi and Bluetooth with a long press in Quick Settings.

System
New New 10-inch tablet UI which lets you quickly access your favorite apps from any homescreen and gives improved access to your notifications.
New New multi-user support for tablets lets different users have their own separate, customizable spaces on a single device.
New Tablets can now support up to eight users. Three users can be active at a time, and they can all sync data like email at the same time and even reuse apps if another user has them installed.
New A new display mode ‘Daydream’ allows apps to display interactive screensavers - like a photo album or a Currents stream when your tablet or phone isn’t being used.
New App permissions are now clearer and more intuitive.
New Android 4.2 introduces a new app verification service (for devices that have Google Play installed) that provides enhanced security along with always-on VPN.
New You'll now receive a warning before an app tries to send SMS messages that may cost you money.
New Improved security for devices with debugging enabled - you can enable debugging for each new debugging client.

Google Search
New Voice Search lets you launch apps, add meetings to your calendar or even find out when your next appointment is.

Google Now
New Hotel card: Get one-touch navigation to your hotel when you arrive in a new city.
New Restaurant reservation card: Be reminded to leave for the restaurant based on live traffic information.
New Event card: Get reminders about events you purchased a ticket for.
New Package card: See when your online orders ship.
New Next appointment card: When you have an appointment, Google Now checks traffic so you can know how long it'll take to get there. You even get a notification for when you should leave.
New Movies card: See showtimes and ratings for what's playing when you're near a theater. Also be notified when a movie you're interested in arrives at theaters.
New Concerts card: See when your favorite artists have concerts at nearby venues.
New Stocks card: Get real-time information about stocks you track.
New Public alerts card: Receive emergency messages such as storm warnings and earthquake alerts.
New Developing story & breaking news card: See breaking news and other developing stories that match your interests.
New Nearby attractions card: See what nearby attractions are popular to visit.
New Nearby photo spots card: Learn of popular photo spots nearby.
New Time at home card: When you're in a different time zone, Google Now shows you the time at home so you never feel too far away.

Calendar
New Calendar can now be displayed as a widget on phone and tablet lock screens.
New Calendar now auto completes when entering event titles.
New New Google Feedback integration lets you give Google feedback and improve Calendar.

Gmail
New Gmail now auto-fits messages to your screen and lets you pinch-to-zoom, so emails are easier than ever to read.
New You can now swipe to archive or delete emails when viewing your Gmail inbox.
New When composing a message, you can attach videos right from Gmail.
New When you receive an email with photos attached, Gmail gives you larger photo previews and a gallery view so you can enjoy the photos more quickly and easily.

Maps
New Upload your Photo Spheres to Google Maps directly from your phone, so others can experience them on their desktop.

Google+
New You can share Photo Spheres with your circles or publicly, and anyone you share with can experience them on Google+ on their desktop.
New Photo Spheres are now also saved in Instant Upload.

Chrome
New Chrome is the standard browser on Nexus 4, Nexus 7 and Nexus 10.

Google Play Music
New You can discover new music in Google Play by touching 'explore similar artists' and swiping between artists to instantly listen to previews of their music.

Google Play Movies and TV Shows
New You can now buy Movies and TV Shows and access your library from Google TV.